is the name of a chemical, discussed by Real Scientists, And Everything. Thanks to Slate's Explainer for the pointer.
Yeah, well, fruit fly genes are named in a way that reminds one of how the mutant looks. You get, for example, "shaker" for a gene who's mutants quiver uncontrollably, etc. Can lead to some linguistic problems (e.g. the gene "fushi tarazu"). So there was already a gene called "hedgehog," and somebody decided to get clever.